Truing AB with rimfire

[Tritiumdials]

I'm having a hard time truing up my AB software on the Kestrel to my DOPE. I'm zeroed at 50 yards with a 22" barrel and on mils.

I can't get the borrowed Labradar to pick up the rifle so I go with the manufacturers website for data on speed. I'm using Center X data for SK STD+, using Center X's G1 at 0.172. I calibrated the MV at the furthest consistent DOPE: 294 yards.

My confirmed DOPE vs Kestrel AB:

100 = 1.8 vs 1.6 (AB)
203 = 7 vs 6.6 (AB)
294 = 11.9 vs 11.9 (AB) [MV calibrated]
489 = 28 vs 25.6 (AB)

I've tried moving MV and BC around to get data to line up but it was always a compromise somewhere. Some are .5+ of deviation between data. I also tried AB's SK STD+ profile and did the same as above with a large disparity of data too.

If I stick with the calibrated MV at 294 and adjusted the BC for the 489 yard [BC is now at 0.138], the 294 yard AB calculated data is 12.7 mil.

What's the best course of action to get a fairly flat consistent calculated data that will do well enough in a match?

 

[usafa77]

DSF explained pretty well in another thread.

 

[Tritiumdials]

Trial 2 using locked environmental data from the same time as the DOPE was obtained:

Using the Center X profile with factory data from the website to be used with SK STD+, I calibrated MV at 203 yards and adjusted DSF for 294 yards using the confirmed 11.9 mils.

Now my data are as follows:
Confirmed DOPE vs Kestrel AB:

100 = 1.8 vs 1.77 (AB)
203 = 7 vs 7.04 (AB) [MV calibrated]
294 = 11.9 vs 11.9 (AB) [DSF calibrated]
489 = 28 vs 25.6 (AB)

This matches fairly well up to the 294 yards. Is there anything else I could do to get a touch closer for distances greater than 294 yards?

 

[usafa77]

Keep walking the DSF out- If you can get a good number at 400 is should (or might) help your 489.

 

[ma smith]

Use a G1 bc of .135 for SK and you will have better luck out of the gate.i'd also confirm your MV at 200 using BC of .135 not .175.

Keep in mind you need perfect/dead nuts laser RF distances to have real dope with rimfire out at 300 and beyond.

 

[littlepod]

Is DSF a Kestrel Elite feature? If so then use the AB Custom Curve instead of the .172 BC.

.172BC is the BC of the bullet at like 50 yards. The BC at 300 yard is around .11.

.135 BC is a great approximation of stuff out to 200yards.

Otherwise I would do DSF at like 100, 150, 200, 250, 300.

 

[Tritiumdials]

I wasn’t aware you could set the DSF to multiple distances.

Trial 3: Center X AB profile with the CDM. Cal MV at 203, DSF at 294 and 489. This gave me pretty good AB results with only .1 off at the 100.

 

[DownhillFromHere]

My $.02 is that trying to obtain and set "precise" 400-yard dope for .22LR is pointless. Consider: if velocity is held constant, there is somewhere around half a mil of scope elevation change between 400 and 405 yards. Factor in the inherent velocity spread of even top-shelf ammo, the ballistic characteristics of the bullet, and environmental factors... anything within about a mil at 400 is "about right." I use the Lapua drag curve with Strelok Pro.

I do "practice" at 400 because targets at that range have started appearing in matches I shoot. So far, target size has been commensurate with the capability of the cartridge (big targets). In practice, I might land two rounds on a 10" plate at 400, then the next five hit high or low with no rhyme or reason other than it's a .22. Yesterday, I had 3" and 4" swingers up at 195 yards. I was thrilled when I hit the 3" disc twice in a row... then the next shot hit high, the 4th low... So I switched to the 4" disc... missed it too. Calm day, cloudy and no mirage...

It's .22.

 

[Timetoshoot]

I’ve doped three loads in three different rifles using this work flow I picked up on the Hide.
zero @50
create .75 inch water line (use a level)on target at 100. adjust muzzle Velocity to true impacts to waterline.
create 2inch water line (use a level) on 200yard target adjust BC to true impacts to waterline.

Dope has been good to 450. Ive found that wind really Corrupts elevation beyond 200 for a 22. The tracks using this method have lined up better than using DSF.. JUST SHARING MY EXPERIENCES

 

[beetroot]

I always start with a MV of 1050 and a BC of .12 to get me started and tune based on results on target.

If your ballistic data matches what you are seeing on target in the real world then you are sorted.

I've found getting elevation at 100, 150 and 200yards is enough to get reliable data.
If you are shooting further than that then you'll have to fine tune based on your future findings.